Greater Armenia (Armenian:Մեծ Հայք, Mets Hayk') is the name given to the state of Armenia that emerged on the Armenian Highlands under the reign of King Artaxias I at the turn of the second century BC. The term was used to refer to Armenian kingdoms throughout the classical, late antique, and medieval periods by contemporary Armenian and non-Armenian authors alike.

To the Romans it was known as Armenia Maior and to the Greek-speaking peoples as Ἀρμενία Μεγάλη (Armenia Megale), to differentiate it with Lesser Armenia (Pok'r Hayk′, in Latin Armenia Minor).[1] It would later be used to distinguish it from the medieval kingdom that was established in Cilicia, which was sometimes referred to as Little Armenia (not to be confused with Lesser Armenia). Though its borders were in a constant state of flux, Greater Armenia roughly encompassed the area stretching from the Euphrates River in the west, the region of Artsakh and parts of Iranian Azerbaijan to the east, parts of the modern state of Georgia to the north, with its southern boundary abutting the northern tip of Mesopotamia.